How is the Roof Constructed? Most homes are designed with rafters spaced 16-inches or 24-inches apart to hold the sheathing upon which the roof shingles or tiles are installed. Skylights are created to fit within these spaces; larger skylights may be installed to provide more light and fresh air and that may require engineering of the roof system. If the roof is constructed with a truss system, and if larger skylights are desired, a structural engineer will need to review the roof and design alternative framing.

Local Building Codes will require permits in most areas for installing skylights to regulate the snow load on the unit, wind resistance, etc.

What is the Architectural Design of the Building? Depending on the historic value of the home, or the curb appeal of its design, skylights may or may not be appropriate on the street side(s) of the home.

How is the Attic Finished? If the skylight has an attic through which the light must travel, a chase will be built to provide access to the room(s) below. Positioning the skylight will be important to take into account any electrical, plumbing or HVAC equipment in the attic.

Venting - Will open and close, like awning windows, to provide fresh air.  May be operated by hand, or be electric with remote control. Units with sensors to close during inclement weather are available.

Fixed - Will not open and close

Roof Window - depends upon the manufacturer, but skylights that open and “pivot” to provide a larger opening and to enable cleaning the outside may be called roof windows. Some manufacturers refer to all skylight options as roof windows, while others call their venting units roof windows. Read manufacturer catalogs and listings for their terminology.

Chase - A tunnel constructed from the skylight through the attic to the room below. The chase walls may be straight, angled or even flared to direct the sunlight and any fresh air, and to provide the view to the sky.

Flashing - Material used to deter water infiltration around protuberances in sheathing, such as windows in walls and skylights or vents in roofs.

Curb - A raised lip surrounding the skylight to deflect water around the unit.

Glazing - Glass or plastics are used in skylights for the viewing area. These units are constructed in single, double, or triple pane varieties. Double and triple pane skylights may opt to have argon gas between the panes to increase the energy efficiency. The glazing can be flat, domed, arched or created into shapes such as pyramids or barrels.

Tempered Glass - Treated by heating and cooling or with chemicals to safety standards. The glass is stronger to resist winds and debris that may hit the skylight. Should it break, tempered glass is designed to create small pieces that will be less damaging if they fall.

Laminated Glass - Two or more panes of glass are bonded with an interlayer of resilient plastic. Used in skylights to diminish fracturing of the panes from storm damage. If the glass breaks, minimal chips of glass will fall into the room below as it will adhere to the plastic laminate.Low-E coatings reduce heat transfer from the outside in, and from the inside out.

U-Factor - The measure of heat transference in a window or skylight. The lower the U-factor, the more energy efficient the unit.

Solar Heat Gain Coefficient (SHGC) - The effectiveness of the skylight in reducing heat from sunlight entering the room.

Visible Light Transmittance - Measurement of the amount of daylight a skylight transmits. To block damaging UV rays, a tinted glazing may be added to the glass or plastic panes. This will block the amount of sunlight into the area below.

Tubular Skylight or Tubular Daylighting Device (TDD) - Designed to provide sunlight through the roof into an area below through a tubular chase, which is treated with a reflective interior coating.

Glass skylights are constructed using glass panes that must be safety rated. Tempered, laminated, or even both types of glass may be used as the panes. Glass skylights will be rated for their solar heat gain and for their energy efficiency.

Plastic skylights use one of several types of plastic materials to create the viewing area. Plastic is easier to mold into shapes so it is most frequently found in arched or domed units. Shaped skylights are used to provide a larger area for sunlight accessibility.

Venting skylights will open to provide fresh air into the space below.

    •  Manual venting units require occupants to open and close the unit. If the skylight is mounted higher than accessible by hand, a pole is supplied to reach the crank for closing.

    •  Motorized venting units are electric or pneumatic and are operated by a wall switch or remote control, even wirelessly, to provide occupants the ability to open and close the skylight.

    •  Automatic venting units are designed with condensation sensors to open and close the skylight automatically.

Fixed skylights provide sunlight and a view to the outside and will not open and closed.

Blinds can be added to a skylight to block the sun’s rays during the hottest time of the day or during the morning hours. Blinds will deflect damaging UV rays from furniture and carpets in the space below. Note the direction of the skylight and realize East and West facing units will provide early morning and late afternoon sunlight into the space below. Blinds can be manually controlled or by use of a remote control.

Shades may be used with skylights to provide “shade” for the room below the skylight. Shades will block damaging UV rays and natural light into the space. Manual or motorized units are available.

Motorized skylights provide the option to open and close venting units by wall switch or remote control. Motorized shades and blinds are available on these units.

Automatic skylights will open and close when condensation sensors recognize the need.

When a full skylight is not practical, a TDD may provide the natural light desired. Smaller than skylights, the TDD fits into tighter spaces.  “Plastic” domes on the roof may be designed with prisms to draw more natural light into the unit and down through a metal or plastic chase through a diffuser into the space below. The tubular chases can be angled and extended from 12-feet up to 24-feet long to reach a lower level space.

How Much Light Is Needed: A 10” TDD will light a 150-square-foot space; a 14” unit provides daylight for a 300-square-foot area; 21” unit will light a 700-square-foot room. Depending upon the reflectivity of the tubular chase, and the length of the run from the roof, from 95 percent to 98 percent of the natural light will reach the room below.

Pitch of the Roof and Type of Shingles: A variety of flashing materials are available to seal the TDD and eliminate leaking. Also, the dome for daylight collection will be angled for best results.

Weather Zones will Require Safety Measures: TDDs are created from materials specified for hurricane and wind load zones.